Analysis of leakage current in ScAlN thin films grown on GaN/sapphire substrates by sputtering epitaxy at various temperatures

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Abstract
The leakage current of ScAlN thin films grown on n + -GaN/sapphire substrates by sputtering epitaxy at growth temperatures of 420 °C, 550 °C, and 600 °C was investigated. As the growth temperature decreased, the device-to-device variation in leakage current was suppressed, and the average breakdown field increased from 3.3 to 4.8 MV cm −1 . The measured leakage current far exceeded that predicted by Fowler–Nordheim tunneling. The temperature-dependent current–voltage characteristics exhibited an exponential increase in leakage current with increasing temperature under both positive and negative bias. Arrhenius analysis revealed that the activation energy depended on the applied electric field, with values typically ranging from approximately 0.4–0.6 eV. This field dependence suggests that multiple transport processes may contribute to the leakage current.
Funding Information
  • Ministry of Education, Culture, Sports, Science and Technology (JPMXP1226UT0104)
  • ACT-X (JPMJAX22KH)
  • Japan Society for the Promotion of Science (JP23KK0094)
  • Fusion Oriented REsearch for disruptive Science and Technology (JPMJFR234D)

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